In Tkinter, I have a window that I would like to create when a process is initialized to run another Python script, which would then close when the script completes. Below is what I have so far:

window = tk.Toplevel()
window.geometry("400x90")
window.wm_title("Process is Running")
process = subprocess.Popen("python3 run_a_script.py", shell=True)
process.wait()
window.destroy()

The script is running, but the popup window never appears. It does appear after the script completes if I remove window.destroy(), but it does not automatically close.

Is there a way to have the window be created before run_a_script.py is run, and then have it automatically close when the script completes?

CodePudding user response：

If I'm interpreting this right, then you never tell the window to "appear". Try adding:

window.update_idletasks()
window.update()

or

window.mainloop()

to show the window

Edit: Also, I typically use tk.Tk() for the main window instead of tk.Toplevel() for clarity. What's the difference between tkinter's Tk and Toplevel classes?

CodePudding user response：

All tkinter updates are handled by the tkinter mainloop and during the execution of the external script, tkinter mainloop does not take the control until after window.destroy(), so you cannot see the window because it has been destroyed when tkinter takes back the control.

To show the window during the execution of the external script, you can:

• call window.update_idletasks() before calling subprocess.Popen(...) to let tkinter to show the window. However you cannot interact with the GUI during the execution of the external script.

window = tk.Toplevel()
window.geometry("400x90")
window.wm_title("Process is Running")
window.update_idletasks() # show the window
process = subprocess.Popen(["python3", "run_a_script.py"])
process.wait()
window.destroy()

• use .after() to check periodically whether the process has completed or not.

window = tk.Toplevel()
window.geometry("400x90")
window.wm_title("Process is Running")
process = subprocess.Popen(["python3", "run_a_script.py"])

def check_process():
    if process.poll() is None:
        # process is still running, check again 100ms later
        window.after(100, check_process)
    else:
        # prcoess is completed, destroy the window
        window.destroy()
check_process() # start the checking